Determination of the acidity constants of some phenol radical cations by means of electron spin resonance

摘要: Phenoxyl radicals were generated in solutions containing from 0 to 75 % sulphuric acid. The changes observed the e.s.r. spectra over this range are shown be due progressive formation of phenol radical cations. In favourable cases plots parameters against acidity enabled us determine pKa cations, which varied –2.0 (phenol cation) –0.8 (hydroquinone cation). Changes coupling constants going a phenoxyl corresponding cation usually relatively small, but g-values change 2.004 4 ± 0.000 2.003 2 4. free energy involved competing oxidative processes discussed and data support view that C—O group resembles ketones.